This is a shortened version of my ultimate list of free Genesis commentaries, created for quicker reference. Commentaries covering the entire book are in boldface.

Those I especially treasured as thorough and thoughtful were the commentaries of Ainsworth, Babington, Kalisch, Needler, and Patrick, the sermons of Candlish and Fuller, and the Genesis Rabbah, a Jewish midrash. Gibbons also has an absurd number of patristic quotations.

Genesis Commentaries

Alcuin (1–16) | Alford | Ambrose (1–4) | Ambrosiaster (“Pseudo-Augustine”) | Anonymous [“Fidus”] (3) | Babington | Basil the Great (1) | H. Bonar (1–6) | Browne (“Speaker’s Commentary”) | Bunyan (1–10) | Bush | Chapman(?) | Clapham (1–14) | Coghlan | Colman (1–3) | T. Cooper | Cumming[1] | | Delitzsch vol 1 (1–14) / Delitzsch vol 2 (15–50) | de Sola, Lindenthal, & Morris | Driver (“Westminster”) | Franks | Geddes | Genesis Rabbah | Gibbons/Gibbens (1–14) | Gibson | Goodspeed | Groves | P. Henry (1–11) | Hughes | Hunnis | “Ibn Ezra” (Abraham ben Meir ibn Ezra) | Jacobus | Jervis | J. C. Jones (1–8) | Keil & Delitzsch | Kurtz / alt. ver. | Latch | Lightfoot | Luther vol 1 (1–3) / Luther vol 2 (4–9) | D. MacDonald (1–3) | McCaul (1) | Murphy | Needler (1–5) | W. Paul | Payne Smith [“Ellicott’s”] | Richardson | A. Ross (1–14) | Ryle / alt. ver.| Sibthorp | Simeon / alt. ver. | Skinner | Spurrell | Terry & Newhall [“Whedon’s”] / alt. ver. | Todd | Turner | Victorinus (1–2) | von Gerlach | Walker (1–2) | J. White (1–3) | Willet | I. Williams (1–4) |

Pentateuch Commentaries

Ainsworth | Blunt | “Chizkuni” (Rabbi Hezekiah ben Manoah) | A. Jackson |Kalisch | Kenrick | Kidder | Morison | “Ramban” (Rabbi Moses ben Nahman) | “Sforno” (Ovadiah ben Ya’akov Seforno) | A. Wright |

Whole Bible Commentaries & Study Bibles

Barnes | Benson | Bullinger | Calvin | Constable | Dodd | Gaebelein | Gill | M. Henry / alt. ver. / abridged ver. | Hewlett | Jamieson | Kitto | Kretzmann | Lange | Meyer[4] | Meyer[5] | Patrick | Poole | T. Scott | Sutcliffe | Trapp | T. Williams |

Sermons & Lectures

Andrewes (1–4) / alt. ver. | Banks (1–3) | Boardman (1–2) | Bonnet (3) | Bonus | Bromby (1–5) | Candlish | Close | Crosse (1–23) | Dods (“Expositor’s Bible”) | Fuller | Horne | MacDuff (28) | Mackintosh | MacLaren [“Expositions of Holy Scripture”] | J. Parker [“People’s Bible” vol. 1] | Rollinson (49) | Shute (16) | Thornton

Studies of Biblical Characters

Cumming[2] (1–11) | Cumming[3] (12–36) | Cumming[4] (37–50) | Kelly (12–25) | Meyer[1] (12–25) | Meyer[3] (25–35) | Meyer[3] (37–50) |

Dissertations & Essays

Barrington (3) | Bate (3) | Gray (14) | Holden (2–3) | Kennicott (2–4) | Oakes (1–3) | Salkeld (2–3) | Shuckford (1–3) |

There are many more works, especially in Latin, that are available online. If you know of a work I’ve left out that’s freely available online, written in English, and in the public domain, please leave a suggestion in the comments.